I've found that Big Al's has better prices, but Foster and Smith has better shipping (they don't charge extra for heavy items like salt), so if you need to buy something heavy, it'll be cheaper at F&S than Big Al's.
I bought my tank, stand and canopy on Ebay, and had great luck (55 gal
with sedona stand and canopy wired with sockets for 4 96 watt PCs) for $250! Craigslist has some good deals too. You just have to be patient and wait for the right item.
I buy livestock and food from my LFS
, and bring them plant clippings for store credit. Occasionally I'll buy something else there if I need it in a big hurry.